The present invention is directed to eubacterial tmDNA sequences and the corresponding tmRNA sequences. The present invention is further directed to alignments of eubacterial tmDNA sequences and use of the sequences and sequence alignments for the development of antibacterial drugs. The present invention is also directed to the use of the sequences for the development of diagnostic assays.
The publications and other materials used herein to illuminate the background of the invention or provide additional details respecting the practice are incorporated by reference, and for convenience are respectively grouped in the appended List of References.
Eubacterial tmRNAs (10Sa RNAs) are unique since they function, at least in E. coli, both as tRNA and as mRNA (for a review, see Muto et al., 1998). These ≈360±10% nucleotide RNAs are charged with alanine at their 3′-ends (Komine et al., 1994; Ushida et al., 1994) and also have a short reading frame coding for 9 to 27 amino acids depending on the bacterial species. E. coli tmRNA mediates recycling of ribosomes stalled at the end of terminatorless mRNAs, via a trans-translation process (Tu et al., 1995; Keiler et al., 1996; Himeno et al., 1997). In E. coli, this amino acid tag is co-translationally added to polypeptides synthesized from mRNAs lacking a termination codon, and the added 11 amino acid C-terminal tag makes the protein a target for specific proteolysis (Keiler et al., 1996).
Structural analyses based on phylogenetic (Felden, et al., 1996; Williams and Bartel, 1996) and probing (Felden et al., 1997; Hickerson et al., 1998) data have led to a compact secondary structure model encompassing 6 helices and 4 pseudoknots. tmRNAs have some structural similarities with canonical tRNAs, especially with tRNA acceptor branches. E. coli tmRNA contains two modified nucleosides, 5-methyluridine and pseudouridine, located in the tRNA-like domain of the molecule, in a seven-nucleotide loop mimicking the conserved sequence of T loops in canonical tRNAs (Felden et al., 1998).
Fifty-three tmRNA sequences are now known from both experimental data and Blast searches on sequenced genomes (summarized in Williams, 1999; Wower and Zwieb, 1999). These sequences cover only 10 phyla, less than one third of the known bacterial taxa. It is desired to determine additional tmRNA sequences and to use the tmRNA sequences for drug development.